Conventional lenses are known which provide a diaphragm drive mechanism on the periphery of lens unit having a diaphragm, and lenses are known which provide a focus drive mechanism on the periphery of lens unit driven in focusing.
These lens drive mechanisms are drive transmission systems such as a gear train, or the like and an actuator such as a motor, and are approximately disposed on the exterior periphery of the lens unit in the diameter direction.
Such mechanisms also are used in zoom lens systems. As the number of zoom components is increased to achieve the high zoom magnification, it is necessary to increase the number of barrels fitted to be extended.
Zoom lenses become bulky, however, in conventional arrangements of focus drive mechanisms and diaphragm drive mechanisms disposed on the exterior periphery of the lens unit in the diameter direction because the dimensions in the diameter direction increase by the increase of the number of barrels in conjunction with the increase in the zoom magnification. In lenses other than zoom lenses, the compactness also is adversely affected.